Fluid catching and signaling stuffing box enclosure

ABSTRACT

A oil well stuffing box containment system is disclosed, which may be used for containing leaks from an oil well stuffing box which is used to seal around the polish rod which is connected to the rod string. The disclosed apparatus comprises a secondary container which encloses the stuffing box, a drain from the secondary container, and a storage container which is used for collecting any liquids which are drained from the secondary container. The secondary container has an upper seal for sealing around the polish rod, and a lower seal which seals around a member of the production tree. A disclosed alternative embodiment provides means for injecting the escaped liquids back into the production system.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] U.S. Prvisional Application No. 60/288,880 was filed for thisinvention on May 3,2001 for which the inventors claim domestic priority.

BACKGROUND OF THE INVENTION

[0002] The present invention is directed to devices that are used forpreventing hydrocarbon spills from oil wells. This invention is moreparticularly directed to an apparatus which prevents oil spillage fromoil well polish rod stuffing boxes, and which may alert the operatorwhen a leak occurs in the stuffing box.

[0003] Many oil wells do not have sufficient pressure at the producingzone to overcome the necessary hydrostatic pressure to produce thereservoir fluids to the ground surface. Producing such wells requiresthe use of some type of artificial lift equipment to bring the oil andassociated water to the ground surface. One of the most common types ofartificial lift devices is the subsurface rod pump. The sub-surface rodpump is run into the well on a string of rods and placed below the fluidlevel maintained within the well. The rod pump, which is usually apositive displacement pump, is operated by reciprocating the string ofrods up and down with a pumping unit set at the ground surface. Thestring of rods is connected to the pumping unit with a polish rod. Astuffing box, set on the production tree which in turn is attached tothe top of the wellhead, encloses packing which seals around the polishrod and allows the polish rod to reciprocate up and down, hopefullymaintaining a fluid-tight seal around the polish rod.

[0004] Unfortunately, stuffing boxes commonly leak. As the polish rodreciprocates through the packing elements, the packing elements begin todeteriorate from friction, heat and abrasion. The operator will commonlyattempt to stop the leakage by tightening the stuffing box or replacingthe packing elements. However, the operator will usually not realizethere is a problem until actually observing a leak from the stuffingbox. If the well is located in a remote location, considerable time maypass before the stuffing box leak is detected, resulting in substantialleakage of oil and other produced fluids. Such releases are undesirablebecause of the potential adverse impact on the environment and wildlife.Such releases can also be costly because of the clean up expense, thepotential liability for fines, and the loss of product. Many regulatoryagencies have adopted a zero tolerance for oil releases into theenvironment and may shut down an operator's producing operation if suchleaks occur.

[0005] The need for an improved stuffing box has long been recognized.However, unlike devices which attempt to solve the problem by modifyingthe stuffing box itself, the present invention adds a secondarycontainment system which prevents leakage even where the stuffing boxfails. The secondary containment system disclosed herein providessubstantial volume for accumulating leaked oil, which is important forwells which are located in remote locations and checked infrequently.Also disclosed herein is a system for providing either an onsite alarm,or providing an alarm to offsite location to alert the operator when astuffing box failure has occurred. This system may also provide forshutting down the pumping unit in the event of a stuffing box leak.

SUMMARY OF THE INVENTION

[0006] The present invention is directed to a stuffing box containmentsystem which satisfies the above-identified need.

[0007] The disclosed apparatus comprises a secondary container whichencloses the stuffing box. The secondary container has two halves, and atop and a bottom. The top of the secondary container has an upper sealwhich seals around the polish rod. The bottom of the secondary containerhas a lower seal which seals around either the bottom of the stuffingbox, the stuffing box body, the tubing nipple, the production flow tee,or other fittings above the production line for the well. The secondarycontainer utilizes a split assembly which forms the two halves whichencapsulate the stuffing box. The two halves are hingedly attachedtogether so the secondary container may be swung open or closed asrequired. Opposite the hinges are fastening means which are used tofasten the two halves of the secondary container around the stuffingbox.

[0008] The bottom of the secondary container has a drain which allowsfluids, which have escaped from a leaking stuffing box, to drain fromthe secondary container into a storage container. The storage containermay be equipped with a pressure relief valve in the event pressurebuilds up from a release of gas from the well or release of associatedgas from any accumulated oil. An alternative embodiment of the inventionincludes a pump for removing fluids from the secondary container andinjecting the fluids into the wellhead flowline.

[0009] The facing edges of the two halves may be sealed with a one piecemolded rubber seal. A unitary seal may be used with the device whichprovides a single seal element for the top seal, the bottom seal, andthe seal for the facing edges of the secondary container. The secondarycontainer may also be equipped with plexiglass windows which allow anoperator to visually inspect the secondary container and determinewhether any liquids have been released into the secondary container. Thesecondary container may also be equipped with a float switch which istriggered if the liquid level in the secondary container reaches apredetermined level. The float switch may be either connected to anonsite alarm device, such as a light or audible alarm to alert theoperator to a stuffing box leak. The float switch may also be connectedto an offsite device, such as a light or alarm to a centralized controlsystem or computer. The float switch may also be connected to the motorcontrol panel for the pumping unit to shut the pumping unit off.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a front view of the disclosed invention, showing theinvention installed on a production tree of an oil well.

[0011]FIG. 2 is a front view of the secondary container, showing how thesecondary container encloses the stuffing box.

[0012]FIG. 3 shows how the disclosed invention seals around the polishrod and the stuffing box.

[0013]FIG. 4 shows a top view of the two halves of the secondarycontainer, with the two halves opened.

[0014]FIG. 5 shows section A-A.

[0015]FIG. 6 shows a top view of the two halves of the secondarycontainer, with the two halves latched closed.

[0016]FIG. 7 shows an alternative embodiment of the secondary container,which uses a tongue and groove seal face.

[0017]FIG. 8 shows the unitary seal which may be used to form the upperand lower seal and the seal between the facing edges of the two halvesof the secondary container.

[0018]FIG. 9 shows a cross-section of the unitary seal.

[0019]FIG. 10 is a front view of an embodiment of the invention whichinjects fluids collected in the secondary container into the wellheadflowline.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] Referring now specifically to the drawings, FIG. 1 shows thedisclosed device installed on an oil well W. The secondary container 10is latched around a stuffing box 12, forming an enclosure around thestuffing box. The secondary container 10 has a top 14 and a bottom 16,the top 14 being sealed around the polish rod 18 and the bottom beingsealed around either the bottom of the stuffing box 12, or some othermember of the production tree 13, such as a tubing nipple or productionflow tee. The secondary container 10 may be any convenient shape formanufacture, installation and storage, including the round containershown in the drawings, or a square container may also be used. Thesecondary container 10 may be manufactured from any suitable material,including carbon steel, fiberglass or high impact plastic. As shown inFIGS. 1 and 2, the secondary container 10 may include either plexiglasswindows 20 or a sight glass, to allow the operator to see whether anyliquids have accumulated inside the secondary container. The secondarycontainer 10 is hinged to hold the two halves together on one side withhinges 22. Latching means 24 are used to hold the two halves together onthe other side. A plurality of stainless steel hinges 22 and latches 24may be used for this purpose.

[0021] The bottom 16 of the secondary container 10 has a drain 26. Asuitable sized drain is 1¼″ or 1½″ equipped with a line pipe thread. Adrain conduit 28 connects the drain to the storage container 30, whichmay be a polytank or some other suitable container. Depending on theexpected maximum pressure, and the pressure rating of the storagecontainer 30, the storage container may be equipped with a pressurerelief valve or vent 32.

[0022] Various elastomeric seals, including rubber, may be used to formthe various sealing means between the secondary container 10, thestuffing box 12, the polish rod 18, and the production tree 13. As shownin FIG. 8, a pair of unitary sealing elements 34 may be used to providesealing elements for all of the surfaces which must be sealed. As shownin FIG. 9, the seal face is grooved to fit the facing edges 36 of thesecondary container 10.

[0023] An alternative embodiment is shown in FIG. 7. In this embodiment,the hinge point 38 for the two halves of the secondary container isoffset from the outside wall of the secondary container 10.

[0024] As known in the industry, the secondary container 10 and/or thestorage container 30 may be equipped with a float switch 40, or othertypes of liquid detection instruments known in the industry, which maybe calibrated to activate from any rising fluid level inside thecontainers. The switch 40 may be used to activate a local or remotealarm, signal a pager and/or provide a shutdown signal to the pumpingunit 42 on the well W. In this manner, an operator may be immediatelynotified if a stuffing box 12 begins to leak, and/or the pumping unit 42may be shut down.

[0025]FIG. 10 depicts an alternative embodiment of the disclosedapparatus. In this embodiment, the pumping unit 42 is equipped with anair cylinder 44, where the piston 46 of the air cylinder is connected toactuating means, which may comprise the walking beam 48 of the pumpingunit. As the walking beam 48 rises, the piston 46 is pulled upwards,pulling suction on the secondary container 10. Fluids contained withinthe secondary container 10 are pulled through the drain 26 through afirst hydraulic conduit 50 and past a first check valve 52 connected tomanifold 54. As the walking beam 48 descends, the piston 46 is strokeddownwards, pushing the fluids suctioned from the secondary container 10past a second check valve 56 into a second hydraulic conduit 58connected to the production tree 13. The air cylinder 44 may be equippedwith a pressure regulator 60 so that the discharge pressure from thecylinder 44 is adjusted to a point sufficiently above the flowlinepressure to allow the fluids from the secondary container 10 to bepumped into a flowline on the production tree 13. The secondarycontainer 10 may also be equipped with an outlet 62 connected to apressure relief valve 64 or vent to relieve any excessive buildup whichmay occur from either a failure of the stuffing box or a failure in thevalving connecting the secondary container to the wellhead flowline.

[0026] The secondary container 10 opens 180 degrees, which allows foreasy application on an existing stuffing box, so it is not necessary toremove the stuffing box to install the secondary container. This featureis important, because removal of the stuffing box usually requires a rigor hoist to pull up on the polish rod.

[0027] While the above is a description of various embodiments of thepresent invention, further modifications may be employed withoutdeparting from the spirit and scope of the present invention. Forexample, the size, shape, and/or material of the various components maybe changed as desired. Thus the scope of the invention should not belimited by the specific structures disclosed.

What is claimed is:
 1. A system for containing an oil well stuffing box,the stuffing box being the type which attaches to a production tree andseals around a polish rod, the polish rod connected on one end to an oilwell pumping unit, and connected on the other end to a rod string which,in turn, is connected to a downhole positive displacement pump, thecontainment system comprising: (a) a secondary container for enclosingthe stuffing box, the secondary container having two halves, each of thehalves having facing edges, the secondary container also having a topand a bottom, and fastening means for fastening the two halves aroundthe stuffing box so the facing edges are abutted together, the containerhaving upper sealing means for sealing around the polish rod, and lowersealing means for sealing around a production tree member, and facingedge sealing means; (b) a drain connected to the bottom of the secondarycontainer to allow fluids, which have escaped from a leaking stuffingbox, to drain from the secondary container; and (c) a storage containerhydraulicly connected to the drain, for receiving fluids which haveescaped from a leaking stuffing box.
 2. The system of claim 1, wherein apressure relief valve is attached to the storage container.
 3. Thesystem of claim 1, wherein the upper sealing means and lower sealingmeans comprise rubber seals.
 4. The system of claim 1, wherein the uppersealing means, the lower sealing means, and the facing edge sealingmeans comprise a pair of unitary seal elements.
 5. The system of claim1, wherein the production tree member is the stuffing box.
 6. The systemof claim 1, wherein the production tree member is a tubing nipple. 7.The system of claim 1, wherein the production tree member is aproduction flow tee.
 8. The system of claim 1 wherein plexiglass windowsare placed in the secondary container, wherein the plexiglass windowsare of the type which allow visual inspection of the secondary containerto determine whether any liquids have been released into the secondarycontainer.
 9. The system of claim 1 wherein a float switch is disposedwithin the secondary container, the float switch being of the type whichis activated if the liquid level in the secondary container reaches apredetermined level.
 10. The system of claim 9 wherein the float switchis connected to an alarm device.
 11. The system of claim 9 wherein thefloat switch is connected to a motor control panel for the pumping unitto shut the pumping unit off if the liquid level in the secondarycontainer reaches a predetermined level.
 12. A system for containing anoil well stuffing box, the stuffing box being the type which attaches toa production tree and seals around a polish rod, the polish rodconnected on one end to an oil well pumping unit having a walking beam,and connected on the other end to a rod string which, in turn, isconnected to a downhole positive displacement pump, the containmentsystem comprising: (a) a secondary container for enclosing the stuffingbox, the secondary container having two halves, each of the halveshaving facing edges, the secondary container also having a top and abottom, and fastening means for fastening the two halves around thestuffing box so the facing edges are abutted together, the containerhaving upper sealing means for sealing around the polish rod, and lowersealing means for sealing around the bottom of the stuffing box, andfacing edge sealing means, the two halves hingedly attached one to theother, so the secondary container may be swung open or closed asrequired; (b) a drain connected to the secondary container; (c) a pistonand cylinder combination operationally attached to actuating means forreciprocating the piston within the cylinder, the piston and cylindercombination being of the type which creates suction when the piston isreciprocated in a first direction and creates pressure when the pistonis reciprocated in a direction opposite to the first direction; (d) afirst hydraulic conduit connecting the drain to a manifold, the manifoldbeing hydraulically connected to the piston and cylinder combination;and (e) a first check valve inserted in the first hydraulic conduitbetween the drain and the manifold, the first check valve so positionedso that when the piston and cylinder combination applies suction to themanifold, the first check valve allows flow from the drain to themanifold, and when the piston and cylinder combination applies pressureto the manifold, the first check valve closes.
 13. The system of claim12, wherein the actuating means comprises connecting the piston to thethe walking beam of the pumping unit, so that the piston is stroked bythe reciprocation of the walking beam.
 14. The system of claim 12,wherein the secondary container has a pressure relief valve.
 15. Thesystem of claim 12, further comprising a second hydraulic conduitconnecting the manifold to the production tree and a second check valve,the second check valve so positioned so that when the piston andcylinder combination applies a pressure to the manifold, the secondcheck valve allows flow from the manifold to the production tree, andwhen the piston and cylinder combination applies suction to themanifold, the second check valve closes.